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Respiration and Circulation Biology 155 A. Russo-Neustadt Respiration and Circulation are coupled processes in most animals The systems function together to exchange gases with the environment and transport them to the tissues I. Types of Respiratory Exchange “Organs”: A. The Body Surface – 1. Requires no respiratory system 2. Animal must be small or thin 3. Must have low oxygen /energy requirements 4. Diffusion alone accounts for gas exchange Oxygen Carbon Dioxide Animals who use their body surface for respiratory exchange include Sponges Jellyfish Flatworms (previous slide) Sea stars B. Gills – 1. Evaginations from the body surface (In mouth to oral cavity over gills and out slit) 2. Used by aquatic animals Gill arch Muscles in oral cavity serve as pump for oneway water flow, due to density of water Animals who use gills for respiratory exchange include Marine worms Clams and mussels Lobsters and shrimp Vertebrate fishes (previous slide) C. “Lungs” Used by terrestrial animals Invaginations from the body surface to decrease water loss Two major types – lungs – used by snails and slugs, vertebrates from amphibians to mammals Tracheal system of insects True a. True lungs – localized exchange surface where oxygen is loaded into the bloodstream Carbon dioxide oxygen Trachea with cartilaginous rings alveolus lung bronchus Bronchial tree Ventilation uses tidal flow of air due to density b. Trachea = system of air filled tubes that branches throughout body Note unique uncoupling between respiratory and circulatory systems Tracheole delivers oxygen to individual cells D. All Respiratory Systems have the Following Things in Common – Large surface area to maximize gas exchange Thin exchange surfaces to maximize the rate of gas exchange D. All Respiratory Systems have the Following Things in Common – continued Gills and true lungs are also – Ventilated = use muscle pumps to keep oxygen rich medium in contact with the exchange surface Perfused = use muscle pumps to move blood through the vessels at the exchange surface to keep oxygen depleted blood in contact with the exchange surface Together these processes ensure a large concentration gradient for oxygen diffusion II. Circulation: A. Components- 1. The cardiovascular system = heart + blood vessels Function = Circulates the blood to and from the tissues 8 Superior vena cava Capillaries of head, chest, and arms Pulmonary artery Pulmonary artery Capillaries of right lung 9 Capillaries of left lung Aorta 2 7 2 3 3 4 5 10 4 Pulmonary vein Right atrium 6 1 9 Pulmonary vein Left atrium Left ventricle Right ventricle Inferior vena cava Aorta 8 Capillaries of abdominal region and legs Right atrium To lung To lung Left atrium From lung From lung Semilunar valve Semilunar valve Atrioventricular (AV) valve Atrioventricular (AV) valve Right ventricle Left ventricle 2. The lymphatic system = lymph vessels + lymph nodes Functions – -immune defense - returns some fluid from the tissues Return of excess fluid from the tissues via the immune system B. Functions of the Circulatory System 1. 2. 3. Transport – oxygen, carbon dioxide, nutrients, wastes and hormones in blood Blood clotting – to seal breaks in vessels, uses platelets and clotting proteins Protection – internal defense using the white blood cells and the lymphatic system C. Types of Circulatory Systems 1. None – Only used by small animals and/or those with low rates of oxygen use b. Circulation occurs due to simple diffusion through the body tissues a. Examples of Animals That Lack a Circulatory System sponges (not shown) jellyfish flatworms sea stars 2. Few vessels Blood leaves vessels, loses pressure, thus low flow, low oxygen demand system (Pump) (Tissue sinuses) Few vessels 3. Blood stays in vessels, thus (pump) high pressure, high flow system for high oxygen demand large vessels (veins) large vessels (arteries, arterioles) Capillaries in tissues for exchange Examples of Animals with an Open Circulatory System clams Crayfish, shrimp, lobsters (not shown) insects as exception to low oxygen use rule (remember the tracheal system) Examples of Animals with a Closed Circulatory System vertebrates from fish to mammals D. The Vertebrate Circulatory System 1. Blood consists of– Plasma = fluid with dissolved substances (examples – nutrients, hormones and most carbon dioxide) b. Cells and cell fragments – a. 1) 2) 3) White blood cells – defense Red blood cells – oxygen transport Platelets – blood clotting 2. Vertebrate hearts and circulatory patterns Note that the evolution of the fourchambered heart of the mammals and birds allows blood to be returned to the heart after exchanging gases at the lungs and to be pumped a second time before traveling to the tissues, needed for high oxygen demand associated with high body temperatures (Pressure declines) CO2 O2 O2 aorta Pulmonary artery aorta Left atrium arteries Pulmonary vein Right atrium Right ventricle CO2 Atrium = receiving chamber Ventricle = pump Vena cava Vena cava CO2 O2 O2 Mammals and And thus blood is pumped twice for a higher pressure, higher flow system CO2 Two-chambered heart with blood pumped once; lower pressure, lower flow system 23.4 The heart contracts and relaxes rhythmically During – – From veins Into heart chambers During – – diastole, blood flows systole, blood flows From atria Into ventricles Copyright © 2009 Pearson Education, Inc. 1 Heart is relaxed. Semilunar valves closed AV valves are open. 0.4 sec Diastole 2 1 Heart is relaxed. Semilunar valves closed Atria contract. 0.1 sec Systole AV valves are open. 0.4 sec Diastole 2 1 Heart is relaxed. Semilunar valves closed Atria contract. 0.1 sec Systole AV valves are open. 0.4 sec 0.3 sec 3 Ventricles contract. Semilunar valves are open. Diastole AV valves closed 3. Generation of the heart beat – note that all cardiac cells are autorhythmic and contract on their own Electrical signals = action potentials pass due to intercalated discs Pacemaker (fastest rate of contraction) = (Holds signal before passing to ventricles, connective tissue between atria and ventricles prevents immediate passage of signal